Carrier 33ZCSECTRM Dokumentacja Pobierz pdf (Strona 20)

The sequence of operation is as follows: when the space

temperature is above the cooling set point and the air source is

in the cooling mode, the zone controller modulates the air ter-

minal’s damper to supply airflow between minimum and maxi-

mum cooling airflow limits. A temperature control loop that

maintains space temperature determines the airflow set point.

As the space temperature falls below the cooling set point, the

PID loop will reduce the airflow. When the space temperature

drops and remains below the cooling set point, the zone con-

troller will hold the airflow at minimum cooling limit.

In its standard operating mode the zone controller follows

the same control sequence for cooling during both occupied

and unoccupied periods. The zone controller’s Occupancy

schedule determines which set point the zone controller will

use.

HEATING — There are two ways to use local heat. Reheat

operates when the zone controller’s zone requires heat and the

air source is supplying cool air to satisfy cooling demand in

other zones. Heat is also used to supplement air source heating

while the air source is supplying heated air, but the temperature

is inadequate to maintain the desired set point.

When the space temperature is below the Heating set point

and the air source is in the heat mode, the zone controller mod-

ulates the air terminals damper to supply airflow between min-

imum and maximum heating CFM (if configured for VAV cen-

tral heating), otherwise the minimum heating airflow is main-

tained. During VAV heating, space temperature PID loop

determines the airflow set point. As the space temperature goes

above the heating set point, the PID loop will start reducing the

airflow. When the space temperature remains above the heat

set point, the zone controller will hold the airflow at minimum

heating CFM.

Reheat

— When the zone controller is applied to a Single Duct

terminal unit and configured for heat, and heating is being

called for in the space, the zone controller reads the space sen-

sor and compares the temperature to the current heating set

point. the zone controller then calculates the required supply air

temperature (submaster reference temperature) to satisfy con-

ditions. The calculated value is compared to the actual temper-

ature supply air and the output is adjusted to satisfy conditions.

The reference temperature is determined by comparing space

temperature with the current biased heating set point.

A Proportional/Integral/Derivative (PID) loop is used

whenever the mode is heating (occupied, unoccupied, or

warm-up).

The heating PID loop maintains the current heating set point

(configured value plus any offset from a 33ZCT56SPT sensor

slide bar).

In a single duct terminal unit equipped with heating, the ter-

minal will provide sufficient airflow for heating (greater of

cooling minimum or reheat values) to the zone whenever heat-

ing is required, as determined by the space temperature sensor

and the set point, if the equipment is supplying cool air. The re-

heat cfm is used to ensure that proper airflow across the heater

is maintained, if the minimum cooling airflow is too low for

safe heating operation.

NOTE: In a system, when the central air source fan is operat-

ing (detected by the linkage master zone controller) ducted

heat will be available to operate.

The zone controller preforms reheat when the space temper-

ature in its zone is below the heating set point and the air source

is delivering cooled air.

During this process, the zone controller also uses the tem-

perature deviation from the heating set point in a PID calcula-

tion to determine a supply-air temperature which will satisfy

the heat demand in the space.

COOLING ONLY — Fig. 6 shows the hardware configura-

tion for a zone controller applied to a single duct air terminal

that is not equipped with heat. The diagram in Fig. 7 shows

how the zone controller controls this type of air terminal.

The terminal provides cooling by modulating its primary air

damper.

A single duct air terminal without local heat can only per-

form heating functions while its air source is delivering heated

air. The control sequence for heating is similar to that for cool-

ing. When the space temperature is below the Heating set

point, the air source is in the heat mode, and VAV heating is en-

abled, the zone controller modulates the air terminal’s damper

to provide supply airflow between minimum and maximum

heating CFM. A temperature PID loop that maintains space

temperature determines the airflow set point. As the space tem-

perature goes above the heating set point, the PID loop will

start to reduce the airflow.

As with cooling operation, the standard heating mode is the

same for occupied and unoccupied periods, differing only in

the set point that the zone controller uses.

Damper Override supersedes the cfm setting the zone con-

troller would otherwise maintain based on space temperature.

The smoke control panel that commands the override mode

must be in accordance with local codes.

STAGED ELECTRIC HEAT — The zone controller can be

configured to control up to three stages of electric heat. The

heat source can be installed in the air terminal (ducted), or as

perimeter heat. Fig. 8 shows the hardware configuration for a

zone controller applied to a single duct air terminal equipped

with ducted staged electric heat. The diagram in Fig. 9 shows

how the zone controller controls this type of air terminal.

The figures depict the electric heat source installed in the air

terminal. When the zone controller is used to control perimeter

heat it follows the same control routines that it uses for terminal

heat. Heat is used in two ways. Heat operates when the zone

controller’s zone requires heating and the air source is supply-

ing cool air to satisfy cooling demand in other zones (reheat).

Heat can also be energized to supplement air source heating

while the air source is supplying heated air.

Staged (electric) heating (1 or 2 stages) is provided by the

33ZCVAVTRM zone controller. Staged (electric) heating

(3 stages) is provided by the 33ZCFANTRM zone controller.

The staging function compares the submaster reference with

the supply-air temperature to calculate the required number of

outputs to energize

The percent output capacity for electric staged heat control

is calculated and displayed.

HOT WATER OR STEAM HEAT — The zone controller

can be configured to control local heat provided by heating

coils carrying hot water or steam, governed either by a two-

position (on/off) valve or by a proportional (floating modulat-

ing) valve. The heating coils can be installed in the air terminal

(ducted), or as perimeter heat. Figure 10 shows the hardware

configuration for a zone controller applied to a single duct air

terminal equipped with ducted hot water or steam heating coils.

The diagram in Fig. 11 shows how the zone controller controls

an air terminal equipped with two-position hot water or steam

heat. The diagram in Fig. 12 shows how the zone controller

controls an air terminal equipped with proportional hot water

or steam heat.

The figures depict the heating coils installed in the air termi-

nal. When the zone controller is used to control perimeter heat

it follows the same control routines that it uses for terminal

heat. Modulating perimeter heating must be hot water, but two-

position may either be hot water or steam heat.

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